Neuroplasmic flow, the intracellular movement of proteins and organelles, supplements the electrically excitable nerve membrane as a medium of communication. The role of neuroplasmic flow in diseases such as peripheral neuropathies and senile dementia is under investigation. In this project we examine the neuronal microtubules and are attempting to elucidate their relationship to neuroplasmic flow. We are using antibody markers for microtubule components. Enzymatic and microscopic assays for neuroplasmic flow supplement information gathered by transmission and scanning electron microscopy. We are also using the photomicrotome, a newly developed instrument for recording serial sections of the whole human brain cinematographically.